Certain colors not showing on Cycles Render
You are using a mathematical multiply. You should be using an RGB multiply 

You can get the color multiply in the add menu Shift-A>Color>MixRGB and set the drop down the multiply.

The reason the math multiply doesn't work is that it simply multiplies a single value (per pixel) together, giving one output channel. The Color multiply multiplies each of the three channels (per pixel) and gives a three channel output.

This is how a multiply RGB node works, using the mathematical multiply:



Each color channel on the first image is multiplied by the corrosponding one on the second image. They are then added together to make a new image.

The factor merely mixes the multiplied image with the un-affected image.